While there exists no eyewitness events to the battle of Guadalete and all source documents were written afterwards, we can, with a little closer reading and contextualisation, begin to piece together a narrative of what most probably took place in and around 711/712.

And it hopefully answers your questions.

First problem, our primary sources of events were written with clear agendas in mind. The ‘Chronica Adefonsi tertii regis’ was an attempt to deliberately try and justify the Kingdoms of Leon as an extension of the Visigothic kingdom and was written almost three centuries later. ‘The Chronicle of 754’ was a Christian account trying to downplay the nature of Christian culpability in the conquest and including many mythic Islamic sources; the ‘Historia Langobardorum’ focuses on Lombardian history and only mentions events involved in our tale in a peripheral way. And finally the account of events by Ibn Abd-el-Hakem was written with an attempt to downplay obvious fractionalisation in the Umayyad forces in the region.

This leaves us having to try and work out a sequence of events that seem consistent with accounts of before and after the period in question.

Supposedly Roderic was the grandson of the tyrannical yet brutally effective Visigothian King Chindasuinth, whose rule was marked by his willingness to kill large numbers of Visigothian nobility in order to gain stability. We can question this heritage insofar as it does seem to create a suitable role-model for him to follow, but if we accept this at face value, then it allows us an insight to the state of the Regnum Visigothorum at the time.

Based on some of the laws passed by King Wamba (who ruled during the 670’s) and accounts of others of the era, we have a nation gripped in a growing series of domestic crisis; political power was gained through strength of arms; fractionalisation was commonplace; violence was endemic and raids from Moorish pirates seem to have been taking place with growing regularity. And this doesn’t even being to mention attempts by Byzantium to claim the region.

What we have here is a fundamentally volatile state- from 589 (when the Visigothian kings embraced Orthodox Christianity) until 711 there had been 18 kings from 15 families in a 122 year period.

Seven of the kings had been deposed or murdered (usually both) and the monarchy in the kingdom was weak, facing numerous revolts and attempted usurpations and only maintaining control via brutality and mass slaughter (as in the model presented to us by Chindasuinth).

The events of Roderic’s accession to the throne reveal that 40 years after Wamba the Regnum Visigothorum was still faced with this chronic instability. By 710 kingship of the Visigoths was held by the young king Wittiza; he had been joint ruler alongside his father until the old man died, and was still only in his 20’s when Roderic made his bid for the throne.

The Chronicle of 754 suggests that Roderic had overthrown the rule of Wittiza by 710 resulting in the violent death of the young king (although I should make it clear many have suggested he died of natural causes).

Whatever the case Roderic was designated King of Toledo, but his rule was, from the very start, contested. While Roderic has nominal control over the region from Portugal (south of the Douro river) and into central Spain, as well as much of the southern coast of Spain (I must emphasise that I only use these names to give you a mental fix in the geography), he lost control of central and western Spain (Tarraconensis) and Narbonne (now the south coast of France).

This breakaway region was ruled by the figure of King Achila, who may have been the infant son of Wittiza, supported by Visigothian nobles who opposed Roderic’s violent usurpation of the throne. We can tell from coins discovered that Achila and Roderic were in opposition with one another but it seems that all out war between the two didn’t break out because of Roderic’s focus on the Berbers.

However it is here that your question seeks to focus on and it is here that we begin to see things as a much more complex situation than later accounts would suggest.

Roderic was opposed by a wide variety of people; his usurpation seems to have been a green light for a rather large ad hoc alliance to have formed against him.

We know that the Byzantines had attempted an large raid of the Visigothic kingdom in 702. Also the entire south coast of the Visigothic kingdom had been conquered and ruled by the Byzantines for nearly 75 years (ending in its reconquest around 90 years previous to the events we are discussing) yet by 710 Byzantine influence in the region seemed limited to the virtually independent fortress of Septem (now modern day Cueta). The fall of the Byzantine province had left it somewhat isolated and it would not be too far a stretch to suggest its rulers sought Visigothian protection in the intervening years.

This is the origin of the later romanticised involvement of the ruler of Septem (a figure named as Urban but later transformed into the mythic figure of Count Julian) who appears to have been the primary instigator of the invasion by the Berbers.

Now if we believe the Muslim tradition that Urban/Julian initiated it to revenge himself upon Roderic for dishonouring his daughter or if we just accept that fact that Roderic was seen as a usurper and Urban/Julian was loyal to Achila, it matters not. What does seem to be the case that Urban/Julian supplied local Berber forces with much needed intelligence and support for an attack upon the King in Toledo.

But he wasn’t alone in this.

It is clear that the Basques also opposed Rodrigo and he was out campaigning against them when the Berber invasion came. And indeed while Roderic was marching south to deal with them, the Basques and others marched to attack Toledo. Crucially we know that included in the alliance against Roderic was none other than Odo, ruler of Aquitaine.

Odo’s involvement is highly significant. It reveals an involvement in internal affairs that stretched beyond the borders of Visigothian control; while Toulouse (the former capital of the gothic kingdom) had been taken by the Merovingian Franks two centuries earlier, assimilation into the Frankish kingdoms was far from secure; Odo’s intervention shows that he had an agenda independent of his Merovingian overlords (his involvement is not seen as a Frankish intervention, rather a localised one), which ties into the fact that soon after he rebels against Frankish domination, beginning a three generation long series of rebellions by the region.

But crucially the involvement of Odo and Urban/Julian suggests that an anti-Roderic alliance based beyond the nominal borders of the Visigothic kingdom, an alliance that included included Basques, most of the Visigothian nobility in the west of the Kingdom and the sizeable Hispano-Jewish community as well.

Whatever the case the invasion does NOT seem to have been inspired by religious Jihad; quite the opposite; it was opportunist and brought about by the ongoing political situation. By all measures it appears to have been a continuation of the policy of raiding Berber tribes had carried out some years previously.

If proof was needed of this I believe it lies in the fact that the raid itself was not led by a representative of the Caliph; Tariq Ibn Ziyad was a local Berber who led an army of recent coverts to Islam. There was no significant Arab presence. By all accounts Tariq was the Berber leader invited to become involved by Urban/Julian.

His force landing at what we call Gibraltar Tariq marched his army north and Roderic did an about face from campaigning against the Basques and marched his army south. Whereas we do not have any contemporary accounts of the battle we can surmise from later records that Roderic had with him Visigothian nobles who supported Achila and who withdrew their support either just before or after the fighting started.

We know that Berber and Arab cavalry had an advantage over both Visigothian and Frankish forces due to the use of the stirrup and since the Berber Force appears to have been primarily cavalry, this would have given them a significant advantage. Whatever the case Roderic seems likely to have been killed fighting and the Berbers were triumphant.

And found themselves facing a power vacuum.